V gene of human parainfluenza virus type 2 (hPIV2) , a member of paramyxoviruses, is transcribed into both a V and a P mRNA.The V mRNA is a faithful transcript of the V gene, however the P mRNA is transcribed by RNA editing mechanism in hPIV2-infected mammalian cells. Thus both the P and the V proteins are translated in the cells. We constructed recombinant baculoviruses containing the original V gene, which has seven G residues at its editing site and a manipulated V gene, which has ten G residues at its editing site. Unexpectedly, a small amount of the P protein was synthesized in addition to the V protein when the V gene was expressed in the recombinant baculovirus-infected insect cells. Furthermore, synthesis of the P protein increased when a recombinant baculovirus containing a V gene, which has extended length of G residue atretch, that is ten G residues, at its editing site, was expressed in the insect cells. Both the P and the V proteins were synthesized in in vitro translation of mRNA from the recombinant baculovirus-infected cells. Moreover, both G-residue insertions and a deletion were detected in mRNA.While the P protein was not detected in in vitro translation of the V RNA that was transcribed in vitro by T7 RNA polymerase. These results suggest that the non-templated G residues were inserted and deleted at the transcription level without paramyxovirus L protein.